EP2393677A1

EP2393677A1 - Method for the chassis control of a motor vehicle, and device for carrying out said method

Info

Publication number: EP2393677A1
Application number: EP09795793A
Authority: EP
Inventors: Silke Buettner; Ivica Durdevic; Ralph Boeker; Roman Sankin; Alexander Habenicht; Michael Knoop; Oliver Wagner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2009-02-03
Filing date: 2009-12-28
Publication date: 2011-12-14
Anticipated expiration: 2029-12-28
Also published as: DE102009027939A1; WO2010089007A1; JP2012516803A; CN102300729B; US9045017B2; US20120055745A1; EP2393677B1; CN102300729A; JP5562355B2

Abstract

The invention relates to a method and a device for the chassis control of a motor vehicle which comprises at least one wheel suspension having at least one shock absorber and carrying a vehicle body. Said shock absorber has at least one rebound stage the stiffness of which can be adjusted and a compression stage the stiffness of which can be adjusted, the stiffness of the compression stage being changed, especially increased, for a pressure load of the shock absorber produced by a predetermined body movement, and the stiffness of the rebound stage being additionally changed, especially increased, for a subsequent rebound load of the shock absorber produced by the predetermined body movement, or the stiffness of the rebound stage is changed, especially increased, for a rebound load of the shock absorber produced by a predetermined body movement, and the stiffness of the compression stage is additionally changed, especially increased, for a subsequent compression load of the shock absorber produced by the predetermined body movement.

Description

description

Method for suspension control of a motor vehicle, and device for implementation

The invention relates to a method for the suspension control of a motor vehicle, which has at least one vehicle structure carrying a suspension with a damper.

Furthermore, the invention relates to a device for suspension control of a motor vehicle, in particular for carrying out said method, wherein at least one wheel suspension of the motor vehicle has an adjustable damper.

State of the art

Method for the suspension control of a motor vehicle are known from the prior art. For example, from DE 41 120 04 C2 discloses a method for driving a variable in its damping characteristic damper of a motor vehicle. For this purpose, the damper has a valve which can be adjusted to adjust the damping characteristic, the switches between the damping characteristics to be used to optimize the properties of the motor vehicle being dependent on whether the damper is subjected to pressure or tension. The hardness of the damper, ie the degree of damping, is set in such a way that the movement of the vehicle body is damped.

Disclosure of the invention

According to the invention, at least one wheel suspension bearing a vehicle body is provided with a damper which has a rebound stage that is adjustable in hardness and a compression stage that is adjustable in hardness a certain vehicle body movement generated pressure load changes the hardness of the compression stage, in particular increases, and for a generated by the specific vehicle body movement, then following tensile load, the hardness of the rebound additionally changed, in particular increased or being for a by a certain vehicle body movement tensile stress generated changes the hardness of the rebound, in particular increased, and for a generated by the specific vehicle body movement, then the following pressure load, the hardness of the compression stage is additionally changed, in particular increased. It is thus provided a damper, which is formed in two stages and whose different stages, the compression stage and the rebound, are independently adjusted in their hardness or in their degree of damping. The compression and the rebound are thereby adjusted depending on the particular vehicle body movement in its hardness, wherein initially only one of the stages during a first phase of the vehicle body movement and then the second stage during a subsequent phase of the

Vehicle body movement are adjusted in their hardness. This can work optimally at the respective vehicle body movement phase (pressure load or tensile load) of the damper. In particular, following the vehicle body movement following vehicle body return movement can be attenuated independently. The particular vehicle body movement may, in particular, be a vehicle body movement caused by a braking process and / or by a spa procedure.

Advantageously, the damper has at least one first valve for adjusting the hardness of the pressure stage and at least one second valve for adjusting the

Hardness of the rebound, wherein upstream of a pressure load of the damper generated by the specific vehicle body movement, the first valve for changing, especially increasing, the hardness of the compression stage and during the subsequent pressure load additionally the second valve for changing, in particular increasing, the hardness the rebound is switched, or wherein prior to a generated by the specific vehicle body movement tensile load of the damper, the second valve for changing, especially increasing the hardness of the rebound and during the subsequent tensile load, the first valve for changing, in particular increasing, the hardness of Pressure level is switched. In such a damper, the adjustment of the damper hardness or the degree of damping always takes place in each case powerless idle stroke. Thus, the control command or the switching of the valve associated with the corresponding stage only has its effect when the valve is switched in the unloaded state. In the present case, the first valve is used to adjust the hardness of the pressure stage and the second valve to adjust the hardness of the rebound of the damper. Before an expected pressure load of the damper, which will be generated by the certain vehicle body movement, according to the invention, the first valve to increase the hardness of the compression stage is switched, and then, when the pressure load by the vehicle body movement is actually carried out, the second valve to Increasing the hardness of the rebound stage. The change between the pressure load and the tensile load of the damper occurs regularly when after a vehicle body movement and a vehicle body return movement is expected. By switching the first valve before the pressure load of the damper and the additional switching of the second valve during the successful compression load of the damper to increase the respective degree of damping, the damper can work optimally during the compressive load and during the tensile load. In particular, the Fahrzeugaufbau- return movement can be damped regardless of the vehicle body movement. Accordingly, according to the invention before a tensile load of the damper generated by an expected vehicle body movement the second

Valve to increase the hardness of the rebound and during the tensile load, the first valve to increase the hardness of the compression stage switched. Whether the damper during the vehicle body movement pressure or train load depends essentially on the type of excitation and its arrangement or the arrangement of the suspension having it on the

Motor vehicle off.

Appropriately, when switching the first and / or the second valve for adjusting the hardness of the damper, a global movement of the vehicle body and / or a local movement of the damper are taken into account.

The local movements of the damper are essentially movements excited by unevenness in the road surface. Such movements usually occur with high deflection frequency. In contrast, the global movement of the damper is mainly caused by driving intervention of the driver of the motor vehicle and the associated vehicle body movements. It is essentially due to a lower deflection frequency in the Characterized comparison to local movement. Of course, there are also reciprocal effects. Thus, road bumps can also stimulate global vehicle body movements and driver's driving interventions can result in local movements of the damper. In the advantageous method, therefore, the local movements of the damper and / or the global vehicle body movements of the motor vehicle are preferably determined or determined, and the hardness of the damper is adjusted or controlled and / or regulated on this basis. Advantageously, the damper has an associated electronics with its own microcontroller and connection to a common data bus, so that can be dispensed with a separate central control unit and instead uses an existing control unit of the chassis area (for example, the ESP control unit or a central control unit of the landing gear domain) and can be dispensed with external additional sensors, such as vertical acceleration sensors or spring travel sensors. The local movement of the damper is advantageously evaluated by means of an evaluation unit associated with the damper. The evaluation takes place directly on the damper or in the evaluation unit assigned to the damper. In this way, it is possible to react very quickly to a change in the local movement, whereby the quality of the control and / or regulation of the damper is increased. The evaluation unit can be assigned to the damper or even integrated in it. The global motion is advantageously estimated in an existing control device of the motor vehicle. The global motion caused by driver inputs, such as braking or steering, must be estimated, otherwise control and / or regulation of the damper due to measured movement data of the vehicle body would always run counter to the actual requirements. A detection with body movement sensors and dead times by signal transmission and processing would be too slow. When estimating the global motion, variables such as roll angle, roll rate and / or roll acceleration, pitch angle, pitch rate and / or pitch acceleration of the vehicle body can be determined. The estimation takes place in a forward-looking manner, so that the determined, anticipated vehicle body movement is determined.

Advantageously, an expected global movement in dependence on steering wheel angle, brake pedal position, accelerator pedal position, target acceleration, Target torque and / or estimated at least one actual state variable of the motor vehicle. The sizes mentioned are directly caused by the driver and easily detectable sizes. In particular, the steering wheel angle, the pressure in the master cylinder, requirements of a brake application by driver assistance systems (eg adaptive cruise control: ACC), the requested engine torque (target torque) and the presence of a gear change are evaluated. The signals are usually already present in a driving stabilization system, such as in the aforementioned ESP. The desired acceleration can relate to both a longitudinal acceleration and a transverse acceleration of the vehicle and can also be detected and / or determined by a driver assistance system. Also, the determination of the yaw rate is advantageous and can be done for example from the steering angle.

According to a development of the invention, a global vehicle body motion triggering braking or acceleration process is determined or estimated depending on the brake pedal position and / or the accelerator pedal position. From the brake pedal position results in a negative target acceleration and from the accelerator pedal position a positive target acceleration of the motor vehicle, the negative target acceleration (= deceleration) can also be determined by the brake pressure. By the

Braking process, a pitching motion of the vehicle body is generated about a transverse axis. By means of the method described above, it is possible to dampen the vehicle body movement during a braking operation accordingly. With the start of braking, as soon as a brake request is detected by the brake pedal position, the first valve of damper on the front axle

(Compression) and the second valve of dampers on the rear axle (rebound) to increase the hardness or the degree of damping switched. As a result, the pitching motion of the vehicle body is damped forward when braking takes place. If the braking operation is carried out until the vehicle is at a standstill, the vehicle body then nods back after the vehicle has come to a standstill. Advantageously, therefore, in a braking operation shortly before the stoppage of the motor vehicle, the first valve of the dampers on the rear axle (pressure stage) and the second valve of the dampers on the front axle (rebound) of the motor vehicle to increase the hardness, while using the each second

Valve the rebound of the dampers on the rear axle and by means of the respective valve the pressure level of the damper on the front axle are switched to their respective normal state. The expected vehicle body movement in this case is the rearward nod of the vehicle body when the vehicle comes to a standstill. As described above, the first and second valves are expediently switched such that the degree of damping of the pressure stage of the damper on the rear axle and the degree of damping of the rebound stage on the front axle are increased. According to the above-described advantageous method for suspension control, the second valve of the dampers on the rear axle and the first valve of the dampers on the front axle of the motor vehicle for increasing the standstill, ie during the pitching motion of the vehicle body to the rear Hardness additionally switched. In other words, in addition, the degree of damping of rebound rebound on the rear axle and the degree of damping of the rebound compression of the front axle dampers are increased for the vehicle body return movement made on the rearward pitch. If the vehicle body thus nods backwards after the already muted back-to-back pitch, the pitchback is also damped. Overall, therefore, advantageously a) with the start of braking, the hardness of the compression stages on the front axle and the hardness of the rebound on the rear axle increases b) shortly before the vehicle stops, the hardness of the rebound on the front axle and the

Increases pressure levels at the rear axle, c) while the vehicle body after standing backwards nickt the remaining pressure and rebound stages increased in their hardness and d) switched off after the pitching motion all compression stages and rebound damping stages in their normal position (normal degree of damping). Wherein while b) expediently the pressure stages on the front axle and the rebound stages on the rear axle are switched to their normal state. As a result, the initial pitching moment of the vehicle body is counteracted after braking to a standstill and damped the pitching vibrations generated thereby. For this purpose, in particular brake pressure and longitudinal speed of the motor vehicle are considered, whereby only the ESP sensor system can be used for this purpose. By adjusting the individual damper stages (tensile or compression stage), a counter-torque is generated. Since the counter-torque, due to the structural design of the damper, can not be actively built, the counter-torque acts only as a reaction torque. The adjustment of the respective stage (train or compression stage) must be made before the relative movement between wheel and vehicle body, as the valves in motion can not be switched. As described above, the compression and rebound stages of the opposite axes are set to be predictively harder.

According to a development of the invention, a cornering trip that triggers a global movement is estimated or determined as a function of the steering wheel angle. The vehicle body undergoes global stimulation as soon as the driver makes a lateral course change by the control intervention on the steering wheel by adjusting the steering wheel angle. This excitation leads to a rotational movement of the vehicle body about the longitudinal axis of the vehicle (wobble) due to its inertia.

Advantageously, when cornering by changing the steering wheel angle, the first valve of at least one in the curve outside damper and the second valve of at least one in-curve damper to increase the hardness are switched. Here, therefore, a vehicle-side-dependent control of the damper takes place, whereas an axis-dependent control is performed during the braking process. When cornering, ie when a rolling movement of the vehicle body takes place, the second valve of the at least one outboard in the curve Ne- adjacent damper and the first valve of the at least one in-curve damper to increase the hardness are switched. In other words, when cornering, a compressive load of the outside of the curve damper is expected, and thus the first valve to increase the hardness of the compression stage switched, while the hardness of the rebound of the damper on the inside in the curve side where the Damper experiences a tensile load, for

Increasing the hardness is switched. Before the vehicle body swings back or the vehicle body return movement takes place, the remaining stages of the dampers are also switched to increase the hardness. As a result, the rolling motion of the vehicle body during cornering is minimized and driving comfort is increased.

According to an advantageous development of the invention, the first and / or the second valve are switched only when a determinable, based on the load of the damper threshold for increasing the hardness exceeded. This prevents that the rebound and / or compression of the damper are already adjusted in their degree of damping even with only small deflections. In particular, this prevents that small, rather negligible for the entire vehicle body local deflections or movements of the damper always lead to an adjustment of the hardness.

Advantageously, the first and / or the second valve for reducing the hardness are switched if the threshold value is not reached over a certain period of time. This returns the damper (s) to their original setting.

A development of the invention provides that the local movement is determined on the basis of at least one damper pressure. On the damper so means are provided to determine at least one damper pressure. The damper pressure can be evaluated, for example, in the evaluation unit assigned to the damper in order to determine the local movement. In this case, a (relative) change in the damper pressure can be evaluated.

A development of the invention provides that the local movement is a vertical movement at an attachment point of the damper. The attachment point of the damper indicates the point at which the damper is attached to the motor vehicle, in particular the structure of the motor vehicle. Only the vertical speed is considered. All other speed components are eliminated or included in the vertical speed.

A development of the invention provides that the local movement of a damper force and / or a pressure difference, in particular taking into account a

Characteristic of the damper, is calculated. Thus, first the damper force and / or the pressure difference is determined. This can be done, for example, by determining a plurality of pressures of the damper, it being advantageous to determine the pressure in the pressure stage and the pressure in the rebound stage of the damper. The local movement, described by a damper speed

- That is, the relative speed between a damper piston and a damper tube - can be determined by means of inversion of the damper characteristic from the damper force or from the differential pressure, wherein a characteristic associated with the current valve position is used. A combination of the mentioned calculation approaches is also possible. A development of the invention provides that the damping force and / or the pressure difference from a pressure in an upper chamber of the damper and a pressure in a lower chamber of the damper is determined. So there are provided means to determine the damper pressure both in rebound and in the compression stage. The pressure in the upper chamber corresponds to the pressure of the rebound and the pressure in the lower chamber corresponds to the pressure of the compression stage.

A development of the invention provides that the damper is a one-pipe damper and in particular its damper travel is estimated. With monotube dampers, the damper travel can also be estimated independently of the damper force and the damper speed. For this one evaluates the mean pressure, which increases due to the penetration of the piston rod into the damper with increasing compression travel. The volume compensation takes place with monotube dampers over a gas volume, which is reduced by the volume of the penetrating piston rod.

A further development of the invention provides that the local movement for high-frequency components and / or the global movement for low-frequency components is evaluated. The high-frequency components are, for example, frequencies in the

Range of Radeigenfrequenz, that is about 10 to 15 Hz, while the low-frequency components are frequencies in the range of the natural frequency of the structure of the motor vehicle. The latter are approximately in the range of 1 to 2 Hz. For this purpose, at least one filter may be provided which allows only the high-frequency components and / or only the low-frequency components to pass for the local movement.

A development of the invention provides that from the local movement and the global movement in each case a damper hardness for the compression and for the rebound stage is determined. The damper hardness is determined separately for the global motion and the local motion. For this purpose, various evaluation paths are provided. One evaluation path is used for the local movement and another for the global movement. From both Auswertepfaden results in each case a damping hardness for the compression and rebound. A development of the invention provides that the damper hardness from the local motion and the damper hardness from the global motion are combined to form a total damper hardness. After determining the damper hardness both for the local movement and for the global movement, these are combined to the total damper hardness. In this case, the damping hardness and / or the total damping hardness for the rebound stage and the pressure stage is advantageously treated separately. The damping hardness is usually a value in the range of 0 to 1, where 0 stands for very soft and 1 for very hard.

A development of the invention provides that the damper according to the

Total damper hardness is set. The damper is controlled and / or regulated to behave according to the determined total damper hardness. Thus, it is set not only according to the damper hardness for the local motion or the damper hardness for the global hardness, but according to the combination of the two values.

The device according to the invention is characterized by at least one suspension bearing a vehicle structure with a damper having a rebound adjustable in the rebound rebound and an adjustable in hardness compression stage, wherein for a generated by a certain vehicle body pressure pressure load of the damper, the hardness of the compression stage changed, in particular increased, and for a generated by the specific vehicle body movement, then following tensile load of the damper, the hardness of the rebound additionally changed, in particular increased or being changed for a generated by a certain vehicle body movement tensile load of the damper, the hardness of the rebound , in particular increased, and for a generated by the specific vehicle body movement, then following pressure load of the damper, the hardness of the compression stage additionally changed, in particular increased.

Advantageously, the damper has at least one first valve for adjusting the hardness of the compression stage and at least one second valve for adjusting the hardness of the rebound, wherein before a pressure load of the damper generated by the specific vehicle body movement, the first valve for changing, in particular increasing , the hardness of the pressure stage switched and additionally during the pressure load occurring the second valve for changing, In particular, increasing the hardness of the rebound is switched, or before a generated by a certain vehicle body movement tensile load of the damper, the second valve for changing, in particular increasing, the hardness of the rebound and during the resulting tensile load, the first valve for changing, in particular increasing, the hardness of the compression stage is switched.

A development of the invention provides that the damper has an evaluation unit and / or at least one pressure measuring device and / or an output stage of at least one valve of the damper can be adjusted by means of the evaluation unit. The evaluation unit, the pressure measuring device - ie means for

Measuring the pressure - and the valve together with its associated output stage are associated with the damper and / or integrated therewith.

A development of the invention provides that the evaluation unit is connected to an existing global motion estimating control device of the motor vehicle via a data bus. The control unit is an already existing control unit of the motor vehicle, for example, the ESP control unit or the central control unit of the landing gear domain. With the help of this controller, the global motion is estimated, that is, there is no separate central control device for the device for chassis control provided. The evaluation unit of the damper is connected to this control unit via a data bus, so that data can be exchanged between them. These data include, for example, the damper hardness and the total damper hardness and / or values for the local movement of the damper and / or the global motion of the motor vehicle.

The invention will be explained in more detail below with reference to the embodiments illustrated in the drawing, without any limitation of the invention. Show it:

FIG. 1 shows a schematic representation of a device or a method for the suspension control of a motor vehicle,

FIG. 2 shows a functional structure of the device and the method, FIG. 3 shows a single-tube damper, as can be used for example together with the method and / or the device,

FIG. 4 shows a flow diagram for a block of the functional structure known from FIG. 2,

FIG. 5 shows a flowchart for a further block of the functional structure,

FIGS. 6A and B show a schematic embodiment of the advantageous method during a pitching movement,

FIG. 7 is a block diagram of a state machine;

FIG. 8 shows a block diagram for carrying out the method during a pitching process,

Figure 9 shows an embodiment for carrying out the method in a rolling motion and

Figure 10 is a block diagram for carrying out the method in a rolling process.

1 shows a system structure 1, as it can be used for example in the inventive method and / or the device according to the invention. Provided are four dampers 2, 3, 4 and 5, wherein each damper is associated with a wheel of a motor vehicle (not shown). The dampers 2, 3, 4 and 5 are provided between the wheel and a body of the motor vehicle, so are part of a suspension (also not shown). Each variable damper has pressure sensors 6, a microprocessor 7, two output stages 8, by means of which a valve drive 9 and via this a valve 10 can be actuated in each case. Each of the pressure sensors 6, the output stages 8, the valve actuators 9 and the valves 10 are each associated with a tensile and a pressure stage of the damper 2. One of the pressure sensors 6 thus serves to determine the pressure in the pressure stage, while the other of the Pressure sensors 6 is used to determine the pressure in the rebound stage. By means of power amplifier 8, valve drive 9 and valve 10, respectively the hardness of the compression stage and / or the rebound of the damper 2 can be adjusted.

The output stages 8 are controlled by the microprocessor 7, which evaluates both signals of the pressure sensors 6, and is connected via a data bus 1 1 with an existing control unit 12 of the motor vehicle and exchanges data with this. The control unit 12 is, for example, an ESP control unit. The control unit 12 additionally receives data from a steering angle sensor 13, a sensor for determining the yaw rate and / or the lateral acceleration and / or a pressure sensor 15 for determining the pressure in a brake cylinder (not shown).

The control unit also receives data from an engine control unit 16 and a transmission control system 17. The engine control unit 16 can deliver, for example, the requested engine torque and / or an instantaneous speed of a drive unit of the motor vehicle. The transmission control 17 notifies the control unit 12, for example, which gear is engaged and whether a gear change is currently being performed.

By means of the control unit 12, the global movement or the vehicle body movement is determined and determines a damper hardness from the global movement. The microprocessor 7 of the damper 2, 3, 4 or 5 determines the local movement, in particular from the data of the pressure sensors 6, and calculates from this also a damper hardness. The damper hardness from the global motion is transmitted from the controller 12 via the data bus 1 1 to the microprocessor 7. This determines the overall damping strength from the damper hardness for the local motion and the damper hardness for the global motion. This total damping hardness is then adjusted by means of the end stage 8, the valve drive 9 and the valve 10 on the damper 2, 3, 4 or 5. In this case, the damper hardness or the total damper hardness is determined in each case for the rebound stage and the pressure stage of the damper 2, 3, 4 or 5. The pressure sensors 6, the microprocessor 7, the power amplifiers 8, the valve actuators 9 and the valves 10 of each damper 2, 3, 4, 5 are associated with the respective damper 2, 3, 4 or 5, so damper-local devices. In contrast, the control unit 12 is for evaluating the global motion of the motor vehicle and therefore a central component. The global movement can therefore also be called a central movement. The damper 2 is provided on the left front of the vehicle, the damper 3 front right, the damper 4 rear left and the rear right damper 5.

FIG. 2 shows a functional structure 18, as may be provided in the method according to the invention or the device according to the invention. The motor vehicle, or its wheels and structure, are symbolized by the box 19. On the motor vehicle act various factors, such as the driver - symbolized by the box 20 - and the road - symbolized by the box 21st The respective influences are indicated by the arrows 22 and 22 '. The wheels and the structure of the motor vehicle interact with the dampers 2, 3, 4 and 5, which are represented by the box 23, wherein the interaction is symbolized by the arrow 24. The box 20 thus symbolizes the influences caused by the

Driver of the motor vehicle are caused while the box 21 describes the road influences. In a first functional block 25, the influence of the driver (box 20) is used to estimate the global movement or the vehicle body movement. This is done on the basis of the data available to the control unit 12 from the steering angle sensor 13, the sensor 14, the pressure sensor 15, the engine control 16 and / or the transmission control 17.

Predictive estimation is required because effective global motion suppression can only occur in motion itself. A detection with the structure associated motion sensors would be due to dead times by signal transmission and processing too slow. The first functional block 25 provides global movement quantities such as roll angle, roll rate, roll acceleration and / or pitch angle, pitch rate, pitch acceleration and / or yaw rate, yaw rate, yaw acceleration. The quantities estimated in the first functional block 25 are forwarded to the second functional block 26. In this, the requirements for the setting of the damper for the compression and rebound of the four dampers 2, 3, 4 and 5 are determined from the estimated sizes. For example, with a predicted roll to the right, the compression level of the dampers becomes

3 and 5 on the right side of the motor vehicle and the rebound of the damper. 2 and 4 hardened on the left side of the motor vehicle. When predicting the backswing of the rolling motion (return motion), the other damper settings are additionally hardened. In a predicted pitching forward, the pressure level of the damper 2 and 3 is hardened at the front of the vehicle and the rebound of the damper 4 and 5 at the rear of the vehicle. The first functional block 25 and the second functional block 26 are integrated into the existing presupposed controller 12 of the driving stabilization system (for example, ESP) or in an existing central control unit of the driving value domain. Thus, the damping hardness from the global motion is now available for the compression stage and the rebound stage of the dampers 2, 3, 4 and 5 respectively.

In a third functional block 27, a movement of the dampers 2, 3, 4 and 5 as well as a force acting on the dampers 2, 3, 4 and 5 is determined. This is done from the pressures that were determined by means of the pressure sensors 6. The pressure level is a pressure p _above and the rebound a pressure p _down assigned. The

Damper movement is described for example by the sizes damper speed and / or damper travel (compression travel). Before the pressures determined by means of the pressure sensors 6 are processed, they are first of all processed, that is, possibly corrected by an offset and / or filtered in order to suppress measurement noise. In addition, a monitoring of the pressures can be used to erroneously exclude certain pressures from the following evaluation. The damper force F _steamer can be determined by the equation

r Steamer ~ "top ^' Poben ^" "down ^" Punten

be determined, wherein A and A _n _above _unt e are the upper and lower cross-sectional areas of a damper piston of the damper. 2

The damper speed v _D , that is, a relative speed between the damper piston and a damper tube of the damper 2, 3, 4 and 5 can be determined with two different approaches. First, the damper force F _{0 can be determined} by inversion of the damper characteristic F ₀ = fi (v _D , position of the valve 10) associated with the current valve position. Subsequently, the damper velocity v _{D is determined} by the equation

v _D = fr ¹ (F ₀ , position of the valve 10) calculated.

Likewise, the calculation of the damper speed v _D from a differential pressure Δp = p _above -P _{down may} be provided by means of a characteristic associated with the current position of the valve 10. This is done using the equation

v _D = f ₂ (Δp, position of the valve 10).

These two calculation approaches can be used individually or in combination. In the case of a combination, an arbitration logic decides which value or mean value is used. If the dampers 2, 3, 4, 5 are single-tube dampers, then it is also possible to estimate the damper travel z _steamer independently of the damper force and damper speed. For this purpose one evaluates the mean pressure (p _un ten + Poben) / 2, which increases due to the penetration of the piston rod into the damper 2, 3, 4, 5 with increasing compression travel. The volume compensation takes place with monotube dampers over a gas volume, which is reduced by the volume of the penetrating piston rod. This will be explained below with reference to FIG. From the damper speed, the vertical speed v _{steamer is} estimated at the attachment point of the dampers 2, 3, 4 and 5 by means of a suitable estimation algorithm. For example, a Kalman filter can be used as the estimation method here. An overview of the function of the third functional block 27 is given below with reference to FIG.

The estimated from the pressure signals damper movement variables and / or the damper force are processed in a fourth functional block 28 and a fifth functional block 29. In the fourth function block 28, a road-dependent determination of the damper hardness is made on the basis of the damper movement variables and / or the damper force. This means that the damper hardness is determined by the local motion. Out-of-sump sizes are not used in this determination. The main objectives are to reduce wheel load fluctuations and to improve the comfort in the frequency range of the wheel oscillations, which are in the range of approximately 10 to 15 Hz. As an algorithm, for example, a frequency-selective control comes into consideration. This will be illustrated below with reference to FIG. In the fifth function block 29, information about the movement mode of the vehicle body, that is, about the lifting, rolling (= rolling) and pitching motion, is determined from the damper local information that the third function block 27 provides. Suitable descriptors for the movement of the

Vehicle construction, for example, the lifting speed v _z in the center of gravity of the structure, the roll rate dt _phl and the pitch rate dt _the ta- The aggregation is carried out, for example, according to the equations

v _z = (v _FL + v _FR + v _RL + v _RR ) / 4 dtp _hl = (-v _FL + v _FR -v _RL + v _RR ) / (2-b) dttheta = ("VFL" V _F R + V _RL + VRR) / (2 "L)

In this case, v _{steamers designate} the vertical speed at the body-side fastening point of the respective damper 2, 3, 4 and 5, b the track width and L den

Wheelbase. FL stands for the front left damper, FR front right, RL rear left and RR rear right.

These body movement estimates are used in a sixth function block 30 to control the movement of the body. The sixth function block 30 has set values 33 of the body movement (typically equal to 0) as input values and the estimated body movement quantities derived from the fifth function block 29, for example v _z , dtp _h , and dW _a . From these input variables, the sixth function block 30 determines a damper hardness, each separated according to the tensile and compression stages. Analogous to the second functional block 26, the sixth functional block 30 thus determines the damper hardness which is necessary in order to dampen the global motion of the motor vehicle.

Finally, a seventh functional block 31 serves to combine the damper hardness determined in the second functional block 26 and the sixth functional block 30 into a damper hardness. This combination takes place separately for train and compression stage of the damper 2, 3, 4 and 5 separately. Examples of arbitration approaches to make such a merge include, for example Train = max {Zugι _oka ι _, train _g ι _oba ι}

Pressure = max {pressure | _Oka ι, printing _g ι _oba ι}

Train = Zugι _oka ι + ι train _g _oba ι - train _toka ι ^■ train _g ι ι _oba

Pressure = pressure | _Oka ι + pressure _g ι _oba ι - pressure _bka ι ^■ pressure _gbba ι

In this case, train and pressure respectively denote the setting requirements for the hardness of the damper or the degree of damping. This is specified in a value range from 0 to 1. This is now in the seventh functional block 31 before a damper hardness, which can serve to damp the global motion. This damper hardness from the seventh functional block 31 as well as the damper hardness from the fourth function block 28 in an eighth function block 32 passed. This eighth function block 38 thus has as inputs the damper hardness, which was determined from the local motion and the damper hardness, which were determined from the global motion. In the eighth function block 32 these are summarized to a total damper hardness. This takes place analogously to the seventh functional block 31 or with the same actuation approaches. By means of the determined in the eighth function block 32 total damper hardness, the dampers 2, 3, 4 and 5 are set, as symbolized by the arrow 34.

The fifth function block 29, the sixth function block 30 and the seventh function block 31 are performed in the control unit 12, which belongs, for example, to an already existing drive stabilization system (for example ESP). Optionally, the integration of the aforementioned function blocks 29, 30, 31 in an existing central control unit of the

Chassis domain. If this central control unit has an expanded optical sensor with measurement of the stroke acceleration a _z , the roll rate dt _phl and the pitch rate dW _a , then the fifth function block 29, which performs the calculation of the body movement variables, can be omitted.

The third functional block 27, the fourth functional block 28 and the eighth functional block 32 may be performed in the microprocessor 7 of the dampers 2, 3, 4 and 5.

FIG. 3 shows a single-tube damper 35 which can be used, for example, as damper 2, 3, 4 and 5. At Einrohrdämpfer 35 are means (not dar- provided) to determine the pressure p _above and the pressure p _below . The pressure P _above is present in a chamber 36 above a piston rod 37, while the pressure p is present _below in a chamber 38. Shown in the figure

3 also located in the Einrohrdämpfer 35 gas volume 39th

FIG. 4 shows a structure of the third functional block 27. It can be seen that it has two calculation strings 40 and 41, with the calculation string 40 having the pressure p at the _top and the calculation string 41 having the pressure p _{at the bottom} as the input variable. In both calculation strings 40 and 41, an offset correction is first performed (box 42), then a low-pass filter is applied (box 43) and finally a plausibility check is performed (box 44). Following box 44, the result of the calculation string 40 is output to a first channel 45 and the result of the calculation string 41 to a second channel 46. In the first channel 45 and the second channel 46 is thus an adjusted pressure signal for the pressure p _above or p _down before. The two pressure signals p _above and _below p are respectively as an input to function blocks 47, 48 and 49 used. In the function block 47, an estimate of the damper force is made by means of the pressures, which is then supplied to the function block 48 as an input variable as well as the pressures p _top and p _below . In function block 48, an estimation of the damper speed is performed from these three quantities.

Function block 49 serves to estimate the damper travel. However, this can only be done if a Einrohrdämpfer 35 is provided as a damper 2, 3, 4 or 5. Subsequent to the function block 48, a further function block 50 is provided, in which from the damper speed, the estimate of the vertical movement at the attachment point of the damper 2, 3,

4 or 5 is performed. At an output 51 is therefore the damper force, at an output 52, the damper speed at an output 53, the vertical movement at the attachment point of the damper 2, 3, 4 or 5 and at an output 54 of the damper. The quantities applied to the outputs 51, 52, 53 and 54 can subsequently be used as input variables of the fourth function block 28 and of the fifth function block 29.

FIG. 5 shows by way of example a construction of the fourth functional block 28. This determines the damper hardness from the local movement of the damper 2, 3, 4 or 5. Serve as input, as stated above, the output variables of the third functional block 27. These are applied to an input 55 at. In the fourth functional block 28, a frequency selective drive is used as the algorithm. For this purpose, first the damper motion quantity is evaluated via one or more filters (box 56). For example, filters can be used

Be bandpass filter. Subsequently, an amplitude calculation is performed (box 57). If the determined amplitudes in the relevant frequency range, that is to say limit values defined at the output of the filter (box 56), then a greater hardness of the damper 2, 3, 4 or 5 is required. The output variables of the amplitude calculation are weighted (box 58) and from the result of this weighting a characteristic curve for the rebound stage (box 59) or pressure stage (box 60) of the damper 2, 3, 4 and 5 is determined.

Figures 6A and B show in the embodiment, a motor vehicle 61 with the dampers 2, 3, 4 and 5. Each of the damper 2, 3, 4, 5 respectively has a first valve for adjusting the hardness of the pressure stage and a second valve for adjusting the hardness of the rebound. Before a pressure load of the dampers 2 - 5 generated by an expected vehicle body movement of the vehicle body 62 of the motor vehicle 61, the respective first valve for increasing the hardness of the compression stage and during the resulting pressure load additionally the second valve for increasing the hardness of the rebound is switched. Before a tensile load of the dampers 2 - 5 generated by an expected vehicle body movement, the first (second) valve for increasing the hardness of the rebound stage and during the applied tensile load, the first valve for increasing the hardness of the compression stage is switched accordingly. In which in Figures 6A and

6B, a braking operation takes place in which a pitching movement of the motor vehicle takes place as described above, wherein the motor vehicle 61 nods about a transverse axis Y. During the braking process, the dampers 2 and 3 are thus subjected to pressure and the dampers 4 and 5 to train. If it is detected that the vehicle 61 is to be braked to a standstill, so are shortly before

Standstill the first valves of the dampers 4 and 5 and the second valves of the damper 2 and 3 connected, so that the degree of damping of the compression stage of the damper 4 and 5 and the degree of damping of the rebound of the damper 2 and 3 is increased when the vehicle body 62 nods to the rear , While the vehicle body 62 nods to the rear, in each case the first valve of the

Damper 2 and 3 and the second valve of the damper 4 and 5 connected, so that the remaining damper stages are hardened when the vehicle body swings forward again or nods.

The general strategy can be represented by the state machine 69 shown in FIG. The block diagram, which is shown in Figure 7, shows schematically the implementation of the advantageous method for suspension control. In a first step 63, the dampers 2 to 5 are in their normal state. In this case, as indicated by a box 64, the vehicle condition is always checked to see whether a vehicle body movement, which leads to a pressure and / or tensile loading of the dampers, can be expected.

If a braking is detected, for example, by detecting the brake pedal angle, so in a following step C1, the first valve of the dampers 4 and 5 on the rear axle and the second valve of the dampers 2 and 3 are connected to the front axle to increase the hardness, such as shown in the figure 6A, so that when the vehicle comes to a standstill and on the

Axis Y nods backwards (step 66), the pressure levels of the dampers 4 and 5 and the rebound damping of the dampers 2 and 3 have a higher degree of damping. If a swinging back expected, or the standstill of the vehicle is reached, in a further step C2, the second valve of the damper 4 and 5 and the first valve of the damper 2 and 3 to increase the

Hardness additionally switched so that when the vehicle nods back in a step 67 to the front, the pressure levels of the damper 2 and 3 and the rebound stages of the damper 4 and 5 are hardened. If no further or no determinable threshold value exceeding movements of the vehicle body 62 occur within a determinable / determinable time period

(Step C3), the first and second valves of the dampers 2 to 5 are switched so that the dampers 2 to 5 return to their normal state (Step 63).

The transition conditions of the state machine 69 can be defined as follows: <Ke

Cl => V _x <P ₂ Thus, the braking is detected in the standstill when a certain speed threshold _Pi is _exceeded by the vehicle longitudinal speed V _x and a certain driver _brake pressure p _brake above a threshold P _ßrake is present. The standstill is defined by means of a second speed threshold P ₂ , where P ₂ <Pi. The transition to the initial damper state can be triggered by either that the amplitude of the pitch rate calculated from a model falls below the threshold value and / or has expired for a certain time, as described above. Here 8 _Brake p are represented as p and P _B P _B _{_Brake} as in FIG. The method described above increases ride comfort by minimizing pitching oscillations after braking to a standstill.

The damping control for the pitch damping can thus be subdivided into three states: a) damper 2 to 5 in the normal state (63), b) hard adjustment of the compression and rebound stages of the dampers of the opposite vehicle axles before the pitching movement occurs in the direction of the compression stage ( 66) and c) hard adjustment of the remaining stages (compression and rebound) before the pitch changes direction (67).

FIG. 8 shows a functional diagram for determining and damping the pitching motion of the vehicle body, one block 70 relating to the estimation of the vehicle body movement and another block 71 relating to the control of the valves or dampers 2 to 5. The transition from a) to b) is triggered by the gradients of the brake pressure p _brake , the accelerator pedal position XEngmePedai = x _E p or by the transmission gearshift, whereby a measure for all three operations is defined (U) - The transition from b) to c) occurs after the predicted pitch rate reaches the maximum of the first half-wave. The hard setting of all damper stages is maintained until the

Wank vibration has subsided. The criterion for this is the predicted pitch rate, which is determined from the stationary longitudinal acceleration a _x . In the calculation of the stationary longitudinal acceleration a _x , a distinction is made between the braking case a _xBrake = ä _xB and the acceleration case a _xAc ceieratιon = äxA. In the case of braking, the relationship between the brake pressure in the master cylinder and the longitudinal acceleration is approximately linear. This situation is described in the nick function in the form of ner linear characteristic f ₂ exploited. In addition, the state K of a clutch and the engaged gear i _{G are} taken into account.

In the case of acceleration, the longitudinal acceleration is determined by means of the stationary pulse rate:

F x aceleration m

The driving force F _x is calculated from the engine torque minus the air and road resistance under simplified assumptions:

F _x =, tand

wherein r _dyn the dynamic tire radius, M _Eng i _n e = M _e, the motor drive torque ioear = io the ratio of the transmission, i _D ιfτ the translation of a differential gear, f _rou - m - g ύer rolling resistance, air resistance, and μ - F _{z represent} the frictional resistance. Constants are assumed for all parameters. The distribution of the weight for the rolling resistance calculation is determined as follows:

p _ "-CoG m - a + _{x kl} - ^■ m - g,

L L

where h _{CoG represents} the height of the center of _{gravity of} the vehicle, L the center distance and L ^, L _FÄ the distance of the rear axle or the front axle to the vehicle center of gravity. The necessary longitudinal acceleration can be taken from the last calculation cycle (real-time operating system). The predicted pitch rate (θ j is calculated from the state model and the longitudinal acceleration as input as follows: ^a x ' wherein the dynamic and input matrix map a half-vehicle model N with respect to the vehicle transverse axis Y. The control can be realized in the form of the state machine described above. The state machine reacts to the change in the brake pressure, the accelerator pedal or the engaged gear and the predicted pitch rate. The control command is for each damper 2 to

5 and each stage of the respective damper 2 to 5 is calculated separately from the measure for the pitch excitation / ₄ . The measure for the pitch excitation is calculated as follows: l

Excitation = + f {Gear) -I

The individual terms of the pseudo-size "Excitation" E be limited between -1 and 1, it is itself defined as the percentage amount of the pitch excitation the gradient of the wheel brake pressure p _Bmke sow \ e accelerator travel x _GasPeda ι ^s' md normalized so that the amount of. In addition, the information about the switching operation can be taken into account by means of a discrete function: The control command of the state machine describes a proportional increase in the damping hardness, where 0 means a maximum soft and 1 a maximum hard setting of the damper characteristic Positioning command is done by means of a fuzzy characteristic, which was derived from the following basic rule base:

IF pitch initiation is zero, THEN all pressure levels and all rebound levels remain passive;

IF pitch excitation is positive, THEN pressure levels are hard front and rebound hard behind;

IF pitch excitation negative, THEN compression levels hard back and rebounding front hard

The transition between a) and b) occurs when the following condition has occurred:

\ Excitation> P E, xcitation

[Vx> Py _x Thus, the measure for the pitch excitation excitation E must exceed a certain threshold P _Ex αtatio _n and a certain longitudinal velocity P _{Vx must be} reached in order to trigger the transition from a) to b). The transition to c) occurs when the predicted pitch rate begins to drop (relaxation of the pitching vibration). This is determined by the following formula: at At,

The transition to the initial state a) takes place when the pitch rate has decayed. For this purpose, the amount of the predicted pitch rate is compared with a certain threshold. If the pitch rate is a certain time below this

Threshold, return all damper stages in the initial state a).

Likewise, the inventive method for suspension control for roll damping can be applied, as explained in more detail with reference to Figure 9. FIG. 9 shows the motor vehicle 61 and a longitudinal axis X of the motor vehicle

61. As already described above, the damping control can also be subdivided into three states for roll damping: d) dampers 2 to 5 in the normal state (no damper activation), e) hard adjustment of the compression and rebound stages of the opposite vehicle side and f) hard Adjust the remaining levels before the roll movement changes direction.

The transition to the second state e) is triggered by the Lenkradwinkelgradienten as soon as it exceeds a certain threshold. The transition from e) to f) occurs after the predicted roll rate φ reaches the minimum of the first half-wave. The hard adjustment of all stages is held until the vibration has subsided. The criterion for this is the predicted roll rate, which is determined from the steady-state lateral acceleration a _y using the half-vehicle model. The stationary lateral acceleration can be determined with δ ^ = steering angle at the front axle and V _ch = characteristic speed from the stationary vehicle in-track model as follows:

The predicted roll rate is calculated from the state model and lateral acceleration as an input as follows: '^ l

Wherein the dynamic and input matrix (A and b) depict a half-vehicle model W with respect to the longitudinal axis X. The structure of the entire roll function is shown in FIG. 10, where the function can be separated into two separate subfunctions: prediction, represented by a block 72 and control, represented by a block 73. By means of the prediction of the roll motion, the valves of the dampers 2 become 5 are activated early, before they are loaded by the forces generated by the rolling motion.

The state machine illustrated in FIG. 7 reacts to changes in the steering wheel angle δ as well as the predicted roll rate in the application for rolling motions of the vehicle body. The control command is calculated separately for each damper 2 to 5 and each stage. The control command describes a proportional increase in the damping stiffness of the respective damper stage, where 0 means a maximum soft and 1 a maximum hard setting of the damper characteristic. The calculation of the positioning command is done by means of a fuzzy characteristic, which can be derived from the following basic rule base:

IF steering wheel angle gradient is zero, THEN all pressure levels and all rebound levels remain passive (that is, all damper stages have standard characteristics);

IF steering wheel angle gradient is positive, THEN pressure levels left hard and rebound hard right;

IF steering wheel angle gradient is negative, THEN pressure levels right hard and rebound hard left. As already said, the state machine for the roll function consists of the three states d) e) f), which are traversed sequentially. The first state d) includes the initialization of the controller. The transition to the second state e) takes place when the Wankanregung is detected. This is the case if the following condition is met:

This means that the steering angle speed must exceed a certain threshold and a certain vehicle longitudinal speed must be achieved. If you are in the second state e), the pressure levels are hardened on the opposite side of the roll motion vehicle side. At the same time, the rebound stages of the other side of the vehicle are hardened. The transition from e) to f) occurs when a change in sign of the roll rate is detected. This is recognized by the following condition:

Sign {% _red ) ≠ Sign {φ _Fred ) at At ₁

Thus, a falling roll rate is determined by sign comparison between the predicted roll rate and its gradient. Both signs must remain different for a certain time (avoidance of error detection due to signal noise).

The third state f), as well as during the braking process, means the complete hardening of all damper stages. This ensures that any

Wank vibration is maximally damped. The return to the default setting d) the damper 2 to 5 happens after the suspected rolling motion has subsided. To identify the matter, a band is defined for the predicted roll rate, where the decayed roll rate should be within this band. In addition, at low longitudinal speeds no

Roll damping produced because of the low damping speeds, the difference between the default setting and hard setting is negligible. Thus, all damper levels return to the default setting as soon as a certain speed threshold is reached. The condition for this is defined as follows: K _ee \ ≤ P _φ at At ₂

V _X <P _VX

The features described above offer a variety of driver benefits in terms of ride comfort and agility. On the one hand, the steering feel and also the lateral guidance is improved by reducing the rolling motion, since the self-steering behavior of the vehicle is improved and the vibrations of the wheel contact force are minimized. Furthermore, driving comfort is improved considerably by reducing pitching vibrations and human sensitivity to vertical accelerations. In addition, the

Improves traction and braking performance by reducing wheel load vibrations. Additional sensors for measuring the motion of the vehicle body, such as acceleration sensors or spring travel sensors, are not needed, but already existing signals are used instead. Advantageously, the two adjustment requirements from the pitching and the rolling motion for each individual damper in a suitable manner, for example, with a MAX-O perator. Each path is divided into the prediction of the respective movement and the calculation of the adjustment request to the damper actuators.

Claims

claims

1 . Method for the suspension control of a motor vehicle, the at least one vehicle structure carrying a suspension with at least one

Damper having a rebound adjustable in the rebound and an adjustable in hardness compression stage, wherein for a generated by a certain vehicle body movement pressure load of the damper, the hardness of the compression stage changed, in particular increased, and for a by the specific vehicle body Movement, then the following tensile load of the damper, the hardness of the rebound additionally changed, in particular increased or wherein for a generated by a certain vehicle body movement tensile load of the damper, the hardness of the rebound changed, especially increased, and for a by the specific vehicle Construction movement generated, then following pressure load of the

Damper, the hardness of the pressure level additionally changed, in particular increased.

2. The method according to claim 1, characterized in that the damper has at least a first valve for adjusting the hardness of the compression stage and at least a second valve for adjusting the hardness of the rebound, and wherein before a pressure generated by the particular vehicle body movement of the damper the first valve for changing, in particular increasing, the hardness of the compression stage switched and during the successful pressure load additionally the second valve for changing, in particular increasing, the hardness of the rebound is switched, or that before a generated by a certain vehicle body movement tensile load of the damper the second valve for changing, in particular increasing, the hardness of the rebound and during the tensile load, the first valve for changing, in particular increasing, the hardness of

Pressure level is switched.

3. The method according to any one of the preceding claims, characterized in that when switching the first and / or the second valve for adjusting the hardness of the damper, a global movement of the vehicle structure and / or a local movement of the damper are taken into account.

4. The method according to any one of the preceding claims, characterized in that an expected global movement in dependence of

Steering wheel angle, brake pedal position, accelerator pedal position, target acceleration, target torque and / or at least one actual state variable of the motor vehicle is estimated.

5. The method according to any one of the preceding claims, characterized in that a global movement triggering braking or acceleration operation in dependence on the brake pedal position and / or the accelerator pedal position is determined.

6. The method according to any one of the preceding claims, characterized in that in a braking operation before the stoppage of the motor vehicle each first valve of dampers on a rear axle and the respective second valve of dampers are connected to a front axle of the motor vehicle to increase the hardness and that upon reaching the standstill, the second valve is additionally switched by the dampers on the rear axle and the first valve by the dampers on the front axle of the motor vehicle to increase the hardness.

7. The method according to any one of the preceding claims, characterized in that a global movement triggering cornering is estimated in dependence on the steering wheel angle.

8. The method according to any one of the preceding claims, characterized in that at the initiation of cornering, the first valve of at least one in the curve outer damper and the second valve of at least one in the curve inside damper to increase the hardness are switched and that, when cornering, the second valve of the at least one outer damper located in the curve and the first valve of the at least one inner damper for increasing the hardness are switched.

9. The method according to any one of the preceding claims, characterized in that the first and / or the second valve are switched only when exceeding a determinable threshold value for increasing the hardness.

10. The method according to any one of the preceding claims, characterized in that the first and / or the second valve to reduce the hardness are switched when the threshold is not reached over a certain period.

1 1. Method according to one of the preceding claims, characterized in that the local movement is determined on the basis of at least one damper pressure.

12. The method according to any one of the preceding claims, characterized in that the local movement is a vertical movement at an attachment point of the damper.

13. The method according to any one of the preceding claims, characterized in that the local movement of a damper force and / or a pressure difference, in particular under consideration of a characteristic of the damper is calculated.

14. The method according to any one of the preceding claims, characterized in that the damping force and / or the pressure difference from a pressure in an upper chamber of the damper and a pressure in a lower chamber of the damper are determined.

15. The method according to any one of the preceding claims, characterized in that the damper is a one-tube damper and in particular its damper path is estimated.

16. The method according to any one of the preceding claims, characterized in that the local movement for high-frequency components and / or the global movement is evaluated for low-frequency components.

17. The method according to any one of the preceding claims, characterized in that from the local movement and the global movement in each case a damper hardness for the compression and for the rebound stage is determined.

18. The method according to any one of the preceding claims, characterized in that the damper hardness from the local movement and the damper hardness from the global movement to a total damper hardness are summarized.

19. A device for suspension control of a motor vehicle (61), in particular for carrying out a method according to one or more of the preceding claims, which has at least one vehicle body (62) bearing suspension with a damper (2,3,4,5) having a in the hardness adjustable rebound stage and an adjustable in hardness compression stage, wherein for a pressure generated by a certain vehicle body movement of the damper (2,3,4,5) changes the hardness of the compression stage, in particular increases, and for one by the the following tensile load of the damper (2, 3, 4, 5) additionally modifies, in particular increases, the hardness of the rebound, or in which case it can be increased by a specific vehicle body structure.

Movement generated tensile load of the damper (2,3,4,5) changes the hardness of the rebound, in particular increased, and for a generated by the specific vehicle body movement, then following pressure load of the damper (2,3,4,5) the hardness the pressure level is additionally changed, in particular increased.

20. The apparatus according to claim 19, characterized in that the damper (2,3,4,5) has at least a first valve for adjusting the hardness of the compression stage and at least a second valve for adjusting the hardness of the rebound, and wherein before a by the particular vehicle body movement generated pressure load of the damper (2,3,4,5) the first valve for changing, in particular increasing, the hardness of the compression stage and during the successful pressure load additionally the second valve for changing, in particular increasing, the hardness of Rebound, or that one ahead of a certain vehicle body

Motion generated tensile load of the damper (2,3,4,5) the second valve for changing, in particular increasing, the hardness of the rebound and during the resulting tensile load, the first valve for changing, in particular increasing, the hardness of the compression stage is switched.

21. Device according to one of the preceding claims, characterized in that the damper (2,3,4,5) has an evaluation unit (7) and / or at least one pressure measuring device (6) and / or by means of the evaluation unit (7) an output stage (8) at least one valve (10) of the damper (2,3,4,5) is adjustable.

22. Device according to one of the preceding claims, characterized in that the evaluation unit (7) with an existing, the global motion estimating control unit (12) of the motor vehicle via a data bus (1 1) is connected.